Silicon-containing material

Abstract

This invention relates to a silicon-containing material based on one or more porous particles and silicon, wherein silicon is disposed in the pores and on the surface of the porous particles, and the silicon-containing material has a density of up to 50 μm. 2 The specific surface area, determined by nitrogen adsorption and BET evaluation, is characterized by the porous particles having an average particle resistance of at least 2 kOhm and a reversible delithiation capacity β of up to 100 mAh / g. The invention also relates to a method for producing the silicon-containing material according to the invention, its use as an active material in the anode of a lithium-ion battery, an anode comprising the silicon-containing material according to the invention, and a lithium-ion battery comprising an anode comprising the silicon-containing material according to the invention.

Description

[0001] This invention relates to silicon-containing materials based on porous particles and silicon, methods for producing silicon-containing materials, and their use as active materials in the anode of lithium-ion batteries.

[0002] As a medium for storing electric current, lithium-ion batteries are currently the most advanced practical electrochemical energy storage devices with the highest energy density. They are primarily used in portable electronic devices, tools, and electric vehicles such as bicycles, scooters, and automobiles. Graphite carbon is currently widely used as the active material for the negative electrode (“anode”) of these batteries. However, a drawback is the relatively low electrochemical capacity of graphite carbon, theoretically at most 372 mAh / g graphite, thus only about one-tenth of the electrochemical capacity theoretically achievable with lithium metal. Alternative active materials for the anode use silicon additives, such as those described in EP1730800B1, US 10,559,812B2, US 10,819,400B2, or EP 3335262B1. Silicon and lithium form a binary electrochemically active alloy, allowing for very high electrochemically achievable lithium content of up to 3579 mAh / g silicon [M. Obrovac, VLChevrier Chem. Rev. 2014, 114, 11444].

[0003] The incorporation and removal of lithium ions in silicon are associated with the drawback of very high volume changes, which can reach 300% in the case of complete incorporation. This volume change subjectes the silicon-containing active material to severe mechanical stress, which can eventually lead to the disintegration of the active material. This process (also known as electrochemical polishing) results in the loss of electrical contacts in the active material and electrode structure, and thus leads to a persistent and irreversible loss of electrode capacity.

[0004] Furthermore, the surface of the silicon-containing active material reacts with the electrolyte components, continuously forming a passivated protective layer (solid electrolyte interphase; SEI). The formed components are no longer electrochemically active. The bound lithium within is no longer usable in the system, thus leading to a significant and continuous loss of battery capacity. Due to the significant changes in silicon volume during battery charging and discharging, the SEI periodically breaks down, exposing further unoccupied surfaces of the silicon-containing active material, which are then exposed to further SEI formation. Since the amount of mobile lithium in the full cell (corresponding to usable capacity) is increasingly limited by the cathode material, this is increasingly depleted, and from an application perspective, the battery capacity decreases to an unacceptable level after only a few cycles.

[0005] The reduction in capacity during several charge and discharge cycles is also known as capacity decay or continuous loss and is usually irreversible.

[0006] A series of silicon-carbon composite particles have been described as active materials for lithium-ion battery anodes, wherein silicon is incorporated into porous carbon particles starting from a gaseous or liquid precursor. For example, US 10,147,950B2 describes the deposition of silicon from monosilane SiH4 into porous carbon in a tube furnace or similar furnace type at high temperatures of 300 to 900°C, preferably with the particles stirred, by CVD (“chemical vapor deposition”) or PE-CVD (“plasma-enhanced chemical vapor deposition”). A similar procedure is described in US 10,424,786B1, in which the silicon precursor is introduced as a mixture with an inert gas at a total pressure of 1.013 bar. WO2012 / 097969A1 describes the deposition of ultrafine silicon particles in the range of 1 to 20 nm on a porous carbon support by heating silane, which serves as a silicon precursor, at 200 to 950 °C. The silane is diluted with an inert gas to prevent the deposited silicon particles from agglomerating or forming a thick layer. The deposition is carried out in the pressure range of 0.1 to 5 bar.

[0007] A common feature of silicon-containing materials obtainable by the aforementioned method is that, when used as the active material in the anode of a lithium-ion battery, carbon, in addition to silicon, also contributes to the electrochemical capacity of the silicon-containing material to some extent. Due to the amorphous structure of carbon used in most cases, a disproportionately large amount of lithium is retained in the silicon-containing material during electrochemical cycling within a limited potential window, especially in applications such as mobile phones, where it does not cover the entire theoretically possible range and cannot be used for further cycling (“capture”). Therefore, the total capacity cannot be used, which is disadvantageous for using known silicon-containing materials in such applications.

[0008] Furthermore, a disadvantage is that silicon deposition at temperatures above approximately 800°C is only possible to a limited extent. This is because the high reactivity of amorphous carbon with gaseous silicon precursors can lead to the formation of silicon carbide, which significantly reduces the lithium-ion storage capacity of silicon-containing materials. Silicon carbide, unlike silicon, cannot be used for the electrochemical storage of lithium ions. Additionally, at these high temperatures, there is a risk that at least some of the porosity of the porous particles will be lost due to the sintering process.

[0009] US 9,005,818 B2 describes a silicon-containing anode active material for lithium-ion batteries, obtained by depositing silicon from a gaseous silicon precursor into a mesoporous silica matrix. Based on the weight of the mesoporous silica matrix, the resulting product contains 0.05 to 100% silicon and has a pore volume of 0.2 to 0.5 ml / g as determined by nitrogen adsorption and a pore size of 150 to 1000 m³ / g. 2 / g BET surface area. The initial coulombic efficiency and cycle stability of the corresponding lithium-ion batteries are not yet satisfactory.

[0010] In this context, the aim is to provide a silicon-containing material that, when used as an active material in the anode of a lithium-ion battery, exhibits low initial and continuous loss of available lithium in the battery, thereby achieving high coulombic efficiency, and furthermore, demonstrates stable electrochemical behavior in subsequent cycles. Attenuation or trapping is preferably minimized.

[0011] Surprisingly, this objective can be achieved using a silicon-containing material based on one or more porous particles and silicon, wherein silicon is disposed in the pores and on the surface of the porous particles, and the silicon-containing material has a maximum thickness of 50 μm. 2 The porous particles, characterized by a specific surface area of ​​ / g determined by nitrogen adsorption and BET evaluation, are characterized by having an average particle resistivity of at least 2 kOhm and a reversible delithiation capacity β of up to 100 mAh / g. This is particularly surprising because active materials for lithium-ion batteries (which typically have low electronic conductivity and therefore high particle resistivity) are usually provided with a conductive carbon layer, which, for example, has very low resistance. This is known, for example, in EP 3 678 990A1 for lithium iron phosphate used as a cathode active material, or also for sub-silicon oxide SiOx used as an anode active material, for example, from EP 1 323 783 B1. In this regard, it is generally assumed that the average particle resistivity of the porous particles, as the starting material for silicon-containing materials used as active materials in the anode of lithium-ion batteries, should be less than 2 kOhm to allow full utilization of the capacity of such silicon-containing materials and the necessary conductivity within the electrode. Typically, porous carbon has such a low particle resistivity. Conversely, it has now been surprisingly discovered that even when the average particle resistance of the porous particles is greater than 2 kOhm, the conductivity of the resulting silicon-containing material is sufficient to make it fully usable as an active material in the anode of lithium-ion batteries.

[0012] This invention relates to silicon-containing materials based on one or more porous particles and silicon, wherein silicon is disposed in the pores and on the surface of the porous particles, and the silicon-containing material has a density of up to 50 μm. 2 The porous particles have a specific surface area of ​​ / g as determined by nitrogen adsorption and BET evaluation, characterized in that they possess...

[0013] a) Average particle resistance of at least 2 kOhm, and

[0014] b) Reversible delithiation capacity β of up to 100 mAh / g.

[0015] The porous particles that can be used in silicon-containing materials are any materials having an average particle resistance of at least 2 kOhm and a reversible delithiation capacity β of up to 100 mAh / g, preferably 0 to 100 mAh / g, particularly preferably 2 to 80 mAh / g.

[0016] Preferred materials here are oxides, such as silicon dioxide, aluminum oxide, silicon-aluminum mixed oxides, magnesium oxide, lead oxide, and zirconium oxide; carbides, such as silicon carbide and boron carbide; nitrides, such as silicon nitride and boron nitride; and other ceramic materials, such as those that can be described by the following composition formula:

[0017] Al a B b C c Mg d N e O f Si g , where 0≤a, b, c, d, e, f, g≤1; where at least two coefficients a to g>0 and a*3+b*3+c*4+d*2+g*4≥e*3+f*2.

[0018] Ceramic materials can be, for example, binary, ternary, quaternary, pentagonal, hexavalent, or heptagonal compounds. Preferably, ceramic materials have the following composition formula:

[0019] Non-stoichiometric boron nitride (BN) z Where z = 0.2 to 1,

[0020] Non-stoichiometric carbon nitride (CN) z Where z = 0.1 to 4 / 3,

[0021] Boron carbonitride B x CN z Where x = 0.1 to 20 and z = 0.1 to 20, and x*3 + 4 ≥ z*3,

[0022] Boron nitride oxide (BN) z O r Where z = 0.1 to 1 and r = 0.1 to 1, and 3 ≥ r*2 + z*3.

[0023] Boron carbonitride oxide B x CN z O r Where x = 0.1 to 2, z = 0.1 to 1 and r = 0.1 to 1, and x*3+4≥r*2+z*3,

[0024] silicon carbide Si x CO z Where x = 0.1 to 2 and z = 0.1 to 2, and x*4 + 4 ≥ z*2,

[0025] Silicon carbonitride (Si) x CN z Where x = 0.1 to 3 and z = 0.1 to 4, and x*4+4≥z*3,

[0026] boron carbonitride silicon Siw B x CN z Where w = 0.1 to 3, x = 0.1 to 2, and z = 0.1 to 4, and w*4 + x*3 + 4 ≥ z*3,

[0027] Si-boron-carbon oxide w B x CO z Where w = 0.10 to 3, x = 0.1 to 2 and z = 0.1 to 4, and w*4 + x*3 + 4 ≥ z*2.

[0028] boron carbonitride silicon oxide Si v B w CN x O z Where v = 0.1 to 3, w = 0.1 to 2, x = 0.1 to 4 and z = 0.1 to 3, where v*4 + w*3 + 4 ≥ x*3 + z*2, and

[0029] Silicon boron aluminum oxide carbonitride (Al) u B v Si x CN w O z , where u = 0.1 to 2, v = 0.1 to 2, w = 0.1 to 4, x = 0.1 to 2 and z = 0.1 to 3, where u*3+v*3+x*4+4≥w*3+z*2.

[0030] Preferred porous particles are based on silica, boron nitride, silicon carbide, silicon nitride, or a mixture of these compounds, particularly silica or boron nitride.

[0031] The preferred porous particles are porous boron nitride particles, especially porous silica particles, and particularly preferred are nanoporous silica particles.

[0032] The synthesis of porous particles can typically be based on sol-gel synthesis, as described, for example, by M. Kato, K. Sakai-Kato, T. Toyo'oka, J. Sep. Science, 2005, 28, 1893-1908, for silica gels, aerogels, or dry gels. SiO2 materials with pore sizes in the less than 10 nm range and high pore volume are preferably prepared using very small basic units (SiO2 particles, polyhedral oligomeric silsesquioxane (POSS) units) via a sol-gel method. Pore properties can be tuned, for example, by reaction conditions (such as temperature, catalyst type, and concentration) or, more specifically, by silane functionalization. Other influencing factors include the drying conditions of the gel or its post-treatment, such as annealing. For example, by supercritical drying of the gel, porosities exceeding 90% at pore sizes less than 100 nm can be obtained. Dry gels with pore sizes less than 10 nm can also be obtained by convection drying.

[0033] Porous particles preferably have a density of 0.1 to 7 g / cm³. 3 A preferred concentration is 0.3 to 3 g / cm³. 3 The density was determined using the helium specific gravity bottle method. This is helpful for increasing the gravimetric capacity (mAh / cm³) of lithium-ion batteries. 3 It is advantageous.

[0034] Porous particles have a diameter percentile d 50 The preferred volume-weighted particle size distribution is ≥0.5μm, particularly preferred is ≥1.5μm, and most preferred is ≥2μm. (Diameter percentile d) 50 Preferably ≤20μm, more preferably ≤12μm, and most preferably ≤8μm.

[0035] The volume-weighted particle size distribution of porous particles is preferably at the diameter percentile d. 10 ≥0.2μm and d 90 Between ≤20.0 μm, particularly preferably in d 10 ≥0.4μm and d 90 ≤15.0μm, most preferably at d 10 ≥0.6μm to d 90 Between ≤12.0μm.

[0036] Porous particles have a diameter percentile d 10 The preferred volume-weighted particle size distribution is ≤10μm, particularly preferred is ≤5μm, especially preferred is ≤3μm, and most preferred is ≤2μm. (Diameter percentile d) 10 Preferably ≥0.2μm, particularly preferably ≥0.5μm, and most preferably ≥1μm.

[0037] Porous particles have a diameter percentile d 90A volume-weighted particle size distribution of ≥4μm, and particularly ≥8μm, is preferred. (Diameter percentile d) 90 Preferably ≤18μm, more preferably ≤15μm, and most preferably ≤13μm.

[0038] The volume-weighted particle size distribution of the porous particles has a width d that is preferably ≤15.0 μm, more preferably ≤12.0 μm, particularly preferably ≤10.0 μm, especially preferably ≤8.0 μm, and most preferably ≤4.0 μm. 90 -d 10 The volume-weighted particle size distribution of the porous particles has a width d that is preferably ≥0.6 μm, particularly preferably ≥0.7 μm, and most preferably ≥1.0 μm. 90 -d 10 .

[0039] Volume-weighted particle size distribution can be determined using static laser scattering, the Mie model, and a Horiba LA 950 measuring apparatus with ethanol as the dispersion medium for porous particles, according to ISO 13320.

[0040] For example, porous particles can be separated or aggregated. Porous particles are preferably non-aggregated, and even more preferably non-aggregated. Aggregation generally means that during the production of porous particles, primary particles initially form and grow together, and / or primary particles are connected to each other, for example, via covalent bonds, thus forming aggregates. Primary particles are typically separate particles. Aggregates or separated particles can form clusters. Clusters are, for example, aggregates or loose piles of primary particles connected to each other via van der Waals interactions or hydrogen bonds. Aggregated aggregates can easily break down back into aggregates through ordinary kneading and dispersing processes. If any, aggregates can only be partially broken down into primary particles through these processes. The presence of porous particles in the form of aggregates, clusters, or separated particles can be visualized, for example, using conventional scanning electron microscopy (SEM). In contrast, static light scattering methods used to determine the particle size distribution or particle size of matrix particles cannot distinguish between aggregates and clusters.

[0041] Porous particles can have any shape, i.e., for example, they can be fragmented, flake-shaped, spherical, or needle-shaped, with fragmented or spherical particles being preferred.

[0042] Morphology can be characterized, for example, by sphericity ψ or sphericity S. According to Wadell's definition, sphericity ψ is the ratio of the surface area of ​​a sphere of equal volume to the actual surface area of ​​the bulk. In the case of a sphere, ψ is 1. According to this definition, porous particles preferably have a sphericity ψ of 0.3 to 1.0, particularly preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0043] Sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of a particle onto a surface to the measured circumference U of that projection. In the case of ideally spherical particles, S should have a value of 1. For porous particles, S is based on the percentile of the sphericity distribution. 10 To S 90 The sphericity S is preferably in the range of 0.5 to 1.0, and particularly preferably in the range of 0.65 to 1.0. The sphericity S is measured using an optical microscope, for example, by referring to a photomicrograph of a single particle, or, in the case of particles <10 μm, preferably by scanning electron microscopy using a graphical evaluation with image analysis software (such as ImageJ).

[0044] Porous particles preferably have a density of ≥0.2 cm. 3 / g, with a preferred size ≥0.6cm 3 / g and the optimal value is ≥1.0cm 3 The gas accessible pore volume is measured per gram. This is beneficial for obtaining high-capacity lithium-ion batteries. According to DIN 66134, the gas accessible pore volume is determined by measuring gas adsorption using nitrogen.

[0045] Porous particles are preferably open-celled. Open-celled generally means that the pores are connected to the surface of the particle, for example, via channels, and can preferably exchange material with the environment, especially gaseous compounds. This can be demonstrated by gas adsorption measurements (according to the analysis of Brunauer, Emmett, and Teller, “BET”), i.e., specific surface area.

[0046] Porous particles preferably have a density of ≥50 μm 2 / g, with a preferred concentration of ≥500m 2 / g, optimal value ≥1000m 2 Specific surface area per g. BET surface area is determined according to DIN 66131 (using nitrogen).

[0047] Porous particles can have pores of any diameter, typically falling within the range of macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). Porous particles can be used in any mixture of different pore types. It is preferred to use porous particles with up to 30% macropores based on the total pore volume; particularly preferred are porous particles without macropores; and especially preferred are porous particles with at least 50% of pores having an average pore size less than 5 nm. Porous particles are particularly preferred to have only pores with a pore size less than 2 nm (measured by: pore size distribution in the mesopore range according to DIN 66134, according to BJH (gas adsorption); and pore size distribution in the micropore range according to DIN 66135, according to Horvath Kawazoe (gas adsorption method); and pore size distribution in the macropore range by mercury porosity determination according to DIN ISO 15901-1).

[0048] Preferably, it has a diameter of less than 0.3 cm. 3 / g, preferably less than 0.15cm 3 Porous particles with a gas-inaccessible pore volume of / g. This can also be used to increase the capacity of lithium-ion batteries. The gas-inaccessible pore volume can be determined using the following formula:

[0049] The volume of gas-inaccessible pores = 1 / density of pure material - 1 / density of the framework.

[0050] Here, the density of pure materials is a theoretical density based on the phase composition or density of the pure substance (the density of the material, as if it did not have closed porosity). Data on the density of pure materials can be found by those skilled in the art, for example, at the Ceramic Data Portal of the National Institute of Standards and Technology (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). For example, the density of pure materials for silicon oxide (SiO2) is 2.203 g / cm³. 3 The pure boron nitride (BN) material has a concentration of 2.25 g / cm³. 3 The concentration of pure silicon nitride (Si3N4) is 3.44 g / cm³. 3 The pure material strength of silicon carbide (SiC) is 3.21 g / cm³. 3 The skeletal density is the actual density of porous particles (accessible to gas) determined by the helium specific gravity bottle method.

[0051] For clarity, it should be noted that porous particles are different from silicon-containing materials. Porous particles are used as starting materials for the production of silicon-containing materials. It is generally preferred that silicon is absent, and more particularly, that silicon obtained by depositing silicon precursors is absent, with the silicon located in the pores and on the surface of the porous particles.

[0052] Silicon-containing materials obtained by depositing silicon in the pores and on the surface of porous particles have a diameter percentile d 50 The preferred volume-weighted particle size distribution is in the range of 0.5 to 20 μm. 50 The value is preferably at least 1.5 μm, particularly preferably at least 2 μm. (Diameter percentile d) 50 Preferably, the micrometer is at most 13 μm, and particularly preferably at most 8 μm.

[0053] The volume-weighted particle size distribution of silicon-containing materials is preferably at the diameter percentile d. 10 ≥0.2μm and d 90 Between ≤20.0 μm, particularly preferably in d 10 ≥0.4μm and d 90 ≤15.0μm, most preferably at d 10 ≥0.6μm to d 90 Between ≤12.0μm.

[0054] Silicon-containing materials have a diameter percentile d 10 The preferred volume-weighted particle size distribution is ≤10μm, particularly preferred is ≤5μm, especially preferred is ≤3μm, and most preferred is ≤1μm. (Diameter percentile d) 10 Preferably ≥0.2μm, particularly preferably ≥0.4μm, and most preferably ≥0.6μm.

[0055] Silicon-containing materials have a diameter percentile d 90 A volume-weighted particle size distribution of ≥5 μm, and particularly ≥10 μm, is preferred. (Diameter percentile d) 90 Preferably ≤20.0μm, particularly preferred ≤15.0μm, and most preferred ≤12.0μm.

[0056] The volume-weighted particle size distribution of the silicon-containing material has a width d that is preferably ≤15.0 μm, particularly preferably ≤12.0 μm, more preferably ≤10.0 μm, especially preferably ≤8.0 μm, and most preferably ≤4.0 μm. 90 -d 10 The volume-weighted particle size distribution of the silicon-containing material has a width d that is preferably ≥0.6 μm, particularly preferably ≥0.7 μm, and most preferably ≥1.0 μm. 90 -d 10 .

[0057] Silicon-containing materials are preferably in particulate form. Particles can be separated or aggregated. Silicon-containing active materials are preferably non-aggregated, and even more preferably non-aggregated. The terms separated, aggregated, and non-aggregated have been defined above for porous particles. The presence of silicon-containing materials in aggregate or cluster form can be visualized, for example, using conventional scanning electron microscopy (SEM).

[0058] Silicon-containing materials can have any shape, i.e., for example, in the form of fragments, flakes, spheres or needles, with fragments or spherical particles being preferred.

[0059] According to Wadell's definition, sphericity ψ is the ratio of the surface area of ​​a sphere of equal volume to the actual surface area of ​​the bulk. In the case of a sphere, ψ is 1. According to this definition, silicon-containing materials preferably have a sphericity ψ of 0.3 to 1.0, particularly preferably 0.5 to 1.0, and most preferably 0.65 to 1.0.

[0060] Sphericity S is the ratio of the circumference of an equivalent circle having the same area A as the projection of a particle onto a surface to the measured circumference U of that projection. In the case of ideally spherical particles, S should have a value of 1. For silicon-containing materials, S is based on the percentile of the sphericity distribution. 10 To S 90 The sphericity S is preferably in the range of 0.5 to 1.0, and particularly preferably in the range of 0.65 to 1.0. The sphericity S is measured using an optical microscope, for example, by referring to a photomicrograph of a single particle, or, in the case of particles <10 μm, preferably by scanning electron microscopy using a graphical evaluation with image analysis software (such as ImageJ).

[0061] The cycle stability of lithium-ion batteries can be further improved by the morphology and composition of silicon-containing materials, especially the specific surface area or internal porosity.

[0062] Based on the total weight of the silicon-containing material, the silicon-containing material preferably contains 10 to 90% by weight, more preferably 20 to 80% by weight, particularly preferably 30 to 60% by weight, and especially preferably 40 to 50% by weight of porous particles.

[0063] Based on the total weight of the silicon-containing material (preferably determined by elemental analysis such as ICP-OES), the silicon-containing material preferably contains 10 to 90 wt%, more preferably 20 to 80 wt%, particularly preferably 30 to 60 wt%, and especially preferably 40 to 50 wt% of silicon obtained by deposition from a silicon precursor. If the porous particles contain silicon compounds, such as silicon compounds in the form of silica, the above data can be determined (in wt%) by subtracting the mass of silicon in the porous particles, as determined by elemental analysis, from the mass of silicon in the silicon-containing material determined by elemental analysis and dividing the result by the mass of the silicon-containing material.

[0064] The volume of silicon present in the silicon-containing material obtained by silicon precursor deposition is calculated by dividing the mass fraction of silicon obtained by silicon precursor deposition in the total mass of the silicon-containing material by the density of silicon (2.336 g / cm³). 3 ) obtained.

[0065] The pore volume P of a silicon-containing material is derived from the sum of the gas-accessible pore volume and the gas-inaccessible pore volume. According to Gurwitsch, the gas-accessible pore volume of a silicon-containing material can be determined by gas adsorption measurement using nitrogen, according to DIN 66134.

[0066] The volume of gas-inaccessible pores in silicon-containing materials can be determined using the following formula:

[0067] The volume of gas-inaccessible pores = 1 / density of pure material - 1 / density of the framework.

[0068] The pure material density of a silicon-containing material is a theoretical density, which can be calculated by multiplying the sum of the theoretical pure material densities of the components present in the silicon-containing material by their respective weight-related percentages in the total material. Pure material densities are reported at the Ceramic Data Portal of the National Institute of Standards and Technology (NIST, https: / / srdata.nist.gov / CeramicDataPortal / scd). The determination of framework density is described at the beginning of the following examples. For example, for silicon-containing materials, this results in:

[0069] Pure material density = Theoretical pure material density of silicon * Proportion of silicon (in weight %) + Theoretical pure material density of porous particles * Proportion of porous particles (in weight %).

[0070] Based on the volume of silicon present in the silicon-containing material obtained from silicon precursor deposition, the pore volume P of the silicon-containing material is preferably in the range of 0 to 400 vol%, more preferably in the range of 100 to 350 vol%, and particularly preferably in the range of 200 to 350 vol%.

[0071] The porosity of silicon-containing materials can be either gas-accessible or gas-inaccessible. The volume ratio of gas-accessible porosity to gas-inaccessible porosity in silicon-containing materials is typically in the range of 0 (no gas-accessible pores) to 1 (all pores are gas-accessible). The volume ratio of gas-accessible porosity to gas-inaccessible porosity in silicon-containing materials is preferably in the range of 0 to 0.8, more preferably in the range of 0 to 0.3, and particularly preferably in the range of 0 to 0.1.

[0072] The pores in silicon-containing materials can have any diameter, for example, within the range of macropores (>50 nm), mesopores (2-50 nm), and micropores (<2 nm). Silicon-containing materials can also comprise any mixture of different pore types. Preferably, based on the total pore volume, the silicon-containing material contains up to 30% macropores; particularly preferred are silicon-containing materials without macropores; especially preferred are silicon-containing materials having at least 50% pores with an average pore diameter of less than 5 nm. Particularly preferred are silicon-containing materials comprising only pores with a diameter of at most 2 nm.

[0073] The silicon-containing material has a silicon structure having a structural size of preferably up to 1000 nm, more preferably less than 100 nm, and particularly preferably less than 5 nm in at least one dimension (measured by scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)).

[0074] The silicon-containing material preferably comprises a silicon layer with a thickness of less than 1000 nm, more preferably less than 100 nm, and particularly preferably less than 5 nm (measured by scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)). The silicon-containing material may also comprise silicon in particulate form. The silicon particles have a diameter preferably at most 1000 nm, more preferably less than 100 nm, and particularly preferably less than 5 nm (measured by scanning electron microscopy (SEM) and / or high-resolution transmission electron microscopy (HR-TEM)). Data regarding the silicon particles are preferably related to the circumferential diameter of the particles in the microscope image.

[0075] Silicon-containing materials have up to 50m 2 / g, preferably less than 30m 2 / g, preferably less than 10m 2 Specific surface area per g. BET surface area is determined according to DIN 66131 (using nitrogen). When silicon-containing materials are used as the active material in the anode of lithium-ion batteries, SEI formation can be reduced and the initial coulombic efficiency can be improved.

[0076] Furthermore, the silicon deposited from the silicon precursor in the silicon-containing material may include dopants, such as dopants selected from Li, Fe, Al, Cu, Ca, K, Na, S, Cl, Zr, Ti, Pt, Ni, Cr, Sn, Mg, Ag, Co, Zn, B, P, Sb, Pb, Ge, Bi, rare earth elements, or combinations thereof. Li and / or Sn are preferred. Based on the total weight of the silicon-containing material, the content of dopants in the silicon-containing material is preferably at most 1% by weight, particularly preferably at most 100 ppm, which can be determined by ICP-OES.

[0077] Silicon-containing materials typically exhibit remarkably high stability under compressive loads and / or shear stresses. The compressive and shear stability of silicon-containing materials is demonstrated, for example, by the fact that they show little or no change in their porous structure in SEM images under compressive loads (e.g., during electrode compaction) or shear stresses (e.g., during electrode fabrication).

[0078] Besides porous particles, silicon deposited from silicon precursors, and other additional elements, silicon-containing materials typically include other components. In particular, carbon may also be present. Specifically, carbon may exist in the form of a thin layer with a thickness of at most 1 μm, preferably less than 100 nm, particularly preferably less than 5 nm, and especially preferably less than 1 nm (which can be measured by SEM or HR-TEM). The carbon layer may, for example, exist on the surface of the pores and / or on the outer surface of the silicon-containing material. The order and number of different layers in the silicon-containing material are also arbitrary. For example, on porous particles, a layer of another material different from the material of the porous particles, such as carbon, may first exist, and a silicon layer or a silicon particle layer may be present on top of this. Moreover, on the silicon layer or the silicon particle layer, another material layer, different from or the same as the material of the porous particles, may be present sequentially, regardless of whether there is another material layer different from the material of the porous particles between the porous particles and the silicon layer or the layer composed of silicon particles.

[0079] The silicon-containing material preferably contains ≤50% by weight, particularly preferably ≤40% by weight, and especially preferably ≤20% by weight of additional elements. The silicon-containing material preferably contains ≥1% by weight, particularly preferably ≥2% by weight, and especially preferably ≥3% by weight of additional elements. Weight percentage refers to the total weight of the silicon-containing material. In alternative embodiments, the silicon-containing material does not contain any additional elements.

[0080] The present invention also relates to a method for producing a silicon-containing material according to the invention by thermally decomposing one or more silicon precursors in the presence of one or more porous particles, thereby depositing silicon in the pores and on the surface of the porous particles, the silicon-containing material having a density of up to 50 μm. 2 The porous particles have a specific surface area of ​​ / g as determined by nitrogen adsorption and BET evaluation, characterized in that they possess...

[0081] a) Average particle resistance of at least 2 kOhm, and

[0082] b) Reversible delithiation capacity β of up to 100 mAh / g.

[0083] Silicon-containing materials can be produced in any reactor typically used for depositing silicon from silicon precursors. Reactors preferably belong to the group consisting of fluidized bed reactors, rotary kilns (which can be oriented in any arrangement from horizontal to vertical), and fixed bed reactors (which can operate as open or closed systems, such as pressure reactors). Reactors that allow for uniform mixing of porous particles and the silicon-containing material formed during deposition with the silicon precursor are particularly preferred. This is advantageous for depositing silicon as uniformly as possible within the pores and on the surface of the porous particles. The most preferred reactors are fluidized bed reactors, rotary kilns, or pressure reactors, especially fluidized bed reactors or pressure reactors.

[0084] Silicon is typically deposited from silicon precursors via thermal decomposition. Preferred silicon precursors are selected from silicon-hydrogen compounds, such as monosilanes SiH4, disilanes Si2H6, and more advanced straight-chain, branched, or cyclic homologues, and neopentasilanes Si5H. 12 Cyclohexylsilane Si6H 12 ; chlorosilanes such as trichlorosilane HSiCl3, dichlorosilane H2SiCl2, chlorosilane H3SiCl, tetrachlorosilane SiCl4, hexachlorodisilane Si2Cl6, and higher linear, branched or cyclic homologues such as 1,1,2,2-tetrachlorodisilane Cl2HSi-SiHCl2; chlorinated and partially chlorinated oligosilanes and polysilanes, methylchlorosilanes such as trichloromethylsilane MeSiCl3, dichlorodimethylsilane Me2SiCl2, chlorotrimethylsilane Me3SiCl, tetramethylsilane Me4Si, dichloromethylsilane MeHSiCl2, chloromethylsilane MeH2SiCl, methylsilane MeH3Si, chlorodimethylsilane Me2HSiCl, dimethylsilane Me2H2Si, trimethylsilane Me3SiH, or mixtures of said silicon compounds. Specifically, the silicon precursor is selected from monosilane SiH4, disilane Si2H6, trichlorosilane HSiCl3, dichlorosilane H2SiCl2, chlorosilane H3SiCl, tetrachlorosilane SiCl4, hexachlorodisilane Si2Cl6, and mixtures containing these silanes.

[0085] In addition, one or more reactive components may be introduced into the reactor. Examples of these are based on dopants containing compounds of boron, nitrogen, phosphorus, arsenic, germanium, iron, or nickel. Dopants are preferably selected from ammonia (NH3), diborane (B2H6), phosphine (PH3), germanane (GeH4), arsine (AsH3), and nickel tetracarbonyl (Ni(CO)4).

[0086] Other examples of reactive components are hydrogen or hydrocarbons, particularly selected from aliphatic hydrocarbons having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, such as methane, ethane, propane, butane, pentane, isobutane, hexane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, and cycloheptane; unsaturated hydrocarbons having 1 to 10 carbon atoms, such as ethylene, acetylene, propylene, or butene; isoprene, butadiene, divinylbenzene, vinylacetylene, cyclohexadiene, and cyclooctadiene; cyclic unsaturated hydrocarbons such as cyclopropylene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, cyclopentadiene, dicyclopentadiene, and norbornene; and aromatic hydrocarbons such as benzene, toluene, p-xylene, m-xylene, o-xylene, styrene (vinylbenzene), ethylbenzene, diphenylmethane, or naphthalene. Other aromatic hydrocarbons such as phenol, o-cresol, m-cresol, p-cresol, umbelliferone, nitrobenzene, chlorobenzene, pyridine, anthracene and phenanthrene, myrcene, geraniol, thioterpineol, norcamphor, borneol, isoborneol, camphor, limonene, terpinene, pinene, pinane, carene, phenol, aniline, anethole, furan, furfural, furfuryl alcohol, hydroxymethylfurfural, dihydroxymethylfuran, and mixed fractions containing a variety of such compounds, such as mixed fractions from natural gas condensate, petroleum distillate, coke oven condensate, mixed fractions from product streams from fluid catalytic cracking (FCC), steam cracking, or Fischer-Tropsch synthesis units, or more generally from hydrocarbon streams from wood, natural gas, petroleum, and coal processing.

[0087] The method is preferably carried out in an inert gas atmosphere, such as a nitrogen or argon atmosphere.

[0088] In all other respects, the method can be performed in the conventional manner typically used for silicon deposition from silicon precursors, with the usual modifications customary to those skilled in the art if necessary.

[0089] The present invention further relates to the use of the silicon-containing material according to the invention as an active material in the anode material of a lithium-ion battery, and the use of the anode according to the invention for the production of lithium-ion batteries.

[0090] The anode material is preferably based on a mixture comprising the silicon-containing material according to the invention, one or more binders, graphite optionally as another active material, one or more other conductive components optionally, and one or more additives optionally.

[0091] The present invention further relates to an anode material comprising a silicon-containing material according to the invention, one or more binders, graphite optionally as another active material, one or more other conductive components optionally, and one or more additives optionally.

[0092] By using other conductive components in the anode material, the contact resistance within the electrode and between the electrode and the current collector can be reduced, which improves the current carrying capacity of the lithium-ion battery. Preferred other conductive components are conductive carbon black, carbon nanotubes, or metal particles, such as copper.

[0093] The primary particles of conductive carbon black preferably have a diameter percentile d 10 =5nm and d 90 Volume-weighted particle size distribution between 200 nm and 200 nm. Primary particles of conductive carbon black can also branch like chains, forming structures up to μm in size. Carbon nanotubes preferably have a diameter of 0.4 to 200 nm, more preferably 2 to 100 nm, and most preferably 5 to 30 nm. Metal particles have a diameter percentile d... 10 =5nm and d 90 Volume-weighted particle size distribution between 800 nm and 800 nm.

[0094] Based on the total weight of the anode material, the anode material preferably contains 0 to 95% by weight, particularly preferably 0 to 40% by weight, and most preferably 0 to 25% by weight of one or more other conductive components.

[0095] Based on the total active material present in the anode material, the silicon-containing material may be present in the anode for lithium-ion batteries at a preferred 5 to 100% by weight, more preferably 30 to 100% by weight, and most preferably 60 to 100% by weight.

[0096] Preferred adhesives are polyacrylic acid or its alkali metal salts (especially lithium or sodium salts), polyvinyl alcohol, cellulose or cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, polyimides, especially polyamide-imides, or thermoplastic elastomers, especially ethylene-propylene-diene terpolymers. Polyacrylic acid, polymethacrylic acid, or cellulose derivatives, especially carboxymethyl cellulose, are particularly preferred. Alkali metal salts of the above adhesives, especially lithium or sodium salts, are also particularly preferred. Most preferred are alkali metal salts of polyacrylic acid or polymethacrylic acid, especially lithium or sodium salts. All or preferably a certain proportion of the acid groups in the adhesive may be present in salt form. The adhesive has a preferred molar mass of 100,000 to 1,000,000 g / mol. Mixtures of two or more adhesives may also be used.

[0097] The graphite used can typically be natural or synthetic. Preferably, the graphite particles have a diameter at the percentile d0.05. 10 >0.2μm and d 90 Volume-weighted particle size distribution between <200 μm.

[0098] Examples of additives are pore-forming agents, dispersants, leveling agents, or dopants, such as elemental lithium.

[0099] The preferred formulation of the anode material preferably comprises 5 to 95 wt%, particularly 60 to 90 wt%, of silicon-containing material; 0 to 90 wt%, particularly 0 to 40 wt%, of other conductive components; 0 to 90 wt%, particularly 5 to 40 wt%, of graphite; 0 to 25 wt%, particularly 5 to 20 wt%, of binder; and optionally 0 to 80 wt%, particularly 0.1 to 5 wt%, of other additives, wherein the weight percentages refer to the total weight of the anode material, and the proportions of all components of the anode material add up to 100 wt%.

[0100] The present invention further relates to an anode comprising a current collector coated with an anode material according to the invention. The anode is preferably used in lithium-ion batteries.

[0101] The components of the anode material can be processed into anode ink or anode paste, for example, in a solvent preferably selected from water, hexane, toluene, tetrahydrofuran, N-methylpyrrolidone, N-ethylpyrrolidone, acetone, ethyl acetate, dimethyl sulfoxide, dimethylacetamide and ethanol, and mixtures of these solvents, preferably using rotor-stator machinery, high-energy mills, planetary kneaders, stirred bead mills, vibrating plates or ultrasonic devices.

[0102] The anolyte or anolyte paste preferably has a pH of 2 to 7.5 (e.g., measured at 20°C using a WTW pH340i pH meter with a SenTix RJD probe).

[0103] For example, anodic ink or anodic paste can be applied to copper foil or other current collectors using a doctor blade. According to the invention, other coating methods can also be used, such as spin coating, roller coating, dip coating, tank coating, brush coating, or spray coating.

[0104] Before coating the copper foil with the anode material according to the invention, the copper foil can be treated with a commercially available primer (e.g., based on polymer resins or silanes). The primer can result in improved adhesion to the copper, but it is generally not actually electrochemically active in itself.

[0105] The anode material is preferably dried to constant weight. The drying temperature depends on the components and solvents used. The drying temperature is preferably between 20°C and 300°C, and particularly preferably between 50°C and 150°C.

[0106] The layer thickness, i.e. the dry layer thickness of the anodic coating, is preferably 2 μm to 500 μm, and particularly preferably 10 μm to 300 μm.

[0107] Finally, the electrode coating can be calendered to obtain a defined porosity. Electrodes produced in this manner preferably have a porosity of 15 to 85%, which can be determined by the mercury porosity determination method according to DIN ISO 15901-1. Preferably, 25 to 85% of the pore volume that can be determined in this manner is provided by pores with a diameter of 0.01 to 2 μm.

[0108] The present invention further relates to a lithium-ion battery comprising a cathode, an anode, two conductive connectors to electrodes, a separator, and an electrolyte impregnating the separator and the two electrodes therein, and a housing accommodating designated components, characterized in that the anode comprises a silicon-containing material according to the present invention.

[0109] In the context of this invention, the term lithium-ion battery also includes battery cells. A battery cell typically includes a cathode, an anode, a separator, and an electrolyte. In addition to one or more battery cells, a lithium-ion battery preferably also includes a battery management system. A battery management system is typically used to control the battery, for example using electronic circuitry, particularly for detecting the state of charge, for deep discharge protection, or for overcharge protection.

[0110] The preferred cathode material used may be lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide (doped or undoped), lithium manganese oxide (spinel), lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium vanadium phosphate, or lithium vanadium oxide.

[0111] The separator is preferably an ion-permeable electrically insulating membrane, preferably made of polyolefins, such as polyethylene (PE) or polypropylene (PP), or polyester or corresponding laminates. Alternatively, the separator may be composed of or coated with glass or ceramic materials, which is common in battery manufacturing. As is known, the separator separates the first electrode from the second electrode and thus prevents electrical conductive connections (short circuits) between the electrodes.

[0112] The electrolyte is preferably a solution containing one or more lithium salts (i.e., conductive salts) in an aprotic solvent. The conductive salt is preferably selected from lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium tetrafluoroborate, lithium imide, lithium methylide, LiCF3SO3, LiN(CF3SO2), and lithium borate. Based on the solvent, the concentration of the conductive salt is preferably between 0.5 mol / L and the solubility limit of the corresponding salt. Particularly preferred is 0.8 mol / L to 1.2 mol / L.

[0113] Examples of solvents that may be used are cyclic carbonates, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl carbonate, dimethoxyethane, diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, acetonitrile, organic carboxylic acid esters or nitrile, either alone or in mixtures thereof.

[0114] The electrolyte preferably contains a film-forming agent such as vinylene carbonate or fluoroethylene carbonate. As a result, a significant improvement in the cycle stability of the anode containing the silicon-containing material according to the invention can be achieved. This is mainly attributed to the formation of a solid electrolyte intermediate phase on the surface of the active particles. The proportion of the film-forming agent in the electrolyte is preferably 0.1 to 20.0% by weight, particularly preferably 0.2 to 15.0% by weight, and most preferably 0.5 to 10% by weight.

[0115] To best match the actual capacity of the electrodes in a lithium-ion battery, it is advantageous to balance the materials used for the positive and negative electrodes in terms of quantity. In this context, it is particularly important to form a capping layer on the surface of the electrochemically active material in the anode during the first or initial charge / discharge cycle (so-called formation) of a secondary lithium-ion battery. This top layer is called the "solid electrolyte interphase" (SEI) and is typically composed mainly of electrolyte decomposition products and a certain amount of lithium, thus it is no longer usable for further charge / discharge reactions. The thickness and composition of the SEI depend on the type and quality of the anode material used and the electrolyte solution used.

[0116] In the case of graphite, the SEI is particularly thin. On graphite, there is typically a loss of 5% to 35% of mobile lithium during the first charging step. Correspondingly, the reversible capacity of the battery is also reduced.

[0117] In the case of an anode having a silicon-containing material according to the invention, there is preferably up to 30%, particularly preferably up to 20%, and most preferably up to 10% loss of mobile lithium in the first charging step, which is significantly lower than the values ​​of the prior art described, for example, in US10,147,950B1 for silicon-containing composite anode materials.

[0118] The lithium-ion battery according to the invention can be produced in all conventional forms, such as in wound, folded or stacked forms.

[0119] As stated above, all substances and materials used in the production of the lithium-ion battery according to the invention are known. The manufacture of the components of the battery according to the invention and their assembly to form the battery according to the invention are carried out according to methods known in the field of battery manufacturing.

[0120] The silicon-containing material of the present invention is characterized by significantly improved electrochemical behavior, resulting in lithium-ion batteries with high capacity and excellent application performance. The silicon-containing material according to the invention is permeable to lithium ions and electrons, thus enabling charge transport. Using the silicon-containing material according to the invention can significantly reduce the amount of SEI in lithium-ion batteries. Furthermore, due to the design of the silicon-containing material according to the invention, the SEI no longer separates from the surface of the silicon-containing material according to the invention, or at least separates to a much smaller extent. All of these contribute to the high cycle stability of the corresponding lithium-ion battery. Decay and trapping can be minimized. Moreover, the lithium-ion battery according to the invention exhibits low initial and continuous loss of available lithium in the battery, thus demonstrating high coulombic efficiency.

[0121] The following examples are provided to further illustrate the invention described herein.

[0122] Scanning electron microscopy (SEM / EDX):

[0123] Microscopic analysis was performed using a Zeiss Ultra 55 scanning electron microscope and an energy-dispersive Oxford X-Max 80N x-ray spectrometer. Prior to analysis, carbon vapor deposition was performed on the samples using a Safematic Compact Coating Unit 010 / HV to prevent charging phenomena. Cross-sections of the silicon-containing materials were fabricated at 6 kV using a Leica TIC 3X ion cutter.

[0124] Inorganic analysis / elemental analysis:

[0125] Carbon content was determined using a Leco CS 230 analyzer; oxygen and nitrogen content were determined using a Leco TCH-600 analyzer. Qualitative and quantitative determinations of other elements were performed using ICP (Inductively Coupled Plasma) emission spectrometry (Optima 7300DV, Perkin Elmer). For this purpose, samples were acid-digested (HF / HNO3) in a microwave (Microwave 3000 from Anton Paar). ICP-OES determinations were guided by ISO 11885 "Water quality—Determination of selected elements by inductively coupled plasma emission spectrometry (ICP-OES) (ISO 11885:2007); German version EN ISO 11885:2009", which is used for the analysis of acidic aqueous solutions (e.g., acidified drinking water, wastewater and other water samples, aqua regia extracts from soil and sediments).

[0126] Particle size determination:

[0127] Particle size distribution was determined by static laser scattering using a Horiba LA 950 according to ISO 13320. Special care must be taken in sample preparation to ensure the dispersion of particles in the measurement solution, so as not to measure the size of aggregates rather than individual particles. For the material examined here, these particles were dispersed in ethanol. For this purpose, if necessary, the dispersion was sonicated at 250W for 4 minutes in a Hielscher UIS250V ultrasonic laboratory instrument with an LS24d5 ultrasonic welding electrode prior to measurement.

[0128] BET surface area measurement:

[0129] The specific surface area of ​​a material is measured by the BET method (using nitrogen, determined according to DIN ISO 9277:2003-05) using a Sorptomatic 199090 instrument (Porotec) or an SA-9603MP instrument (Horiba) via gas adsorption of nitrogen.

[0130] Skeletal density:

[0131] According to DIN 66137-2, the skeletal density, i.e. the density of a porous solid, is determined by the helium specific gravity bottle method, based solely on the volume of the pore space from which gas can enter.

[0132] Gas accessible pore volume:

[0133] According to DIN 66134, the gas accessible pore volume is determined by gas adsorption measurement using nitrogen, according to Gurwitsch.

[0134] Determination of reversible delithiation capacity β:

[0135] The capacity of the porous particles or silicon-containing materials was determined in a button half-cell (CR2032 type, Hohsen Corp.). For this purpose, the electrode was made of porous particles or silicon-containing materials and a binder, optionally graphite, optionally other conductive components, and optionally additives, and mounted against a lithium counter electrode (Rockwood Lithium, 0.5 mm thick, 15 mm diameter). The working electrode based on the silicon-containing material corresponds to the positive electrode in this battery structure. Metallic lithium was used as the counter electrode, which represents the negative electrode. A glass fiber filter paper (Whatman, GD D type) saturated with 120 μl of electrolyte was used as the separator (Dm = 16 mm). The electrolyte used was a 1.0 mol solution of lithium hexafluorophosphate in a 1:4 (v / v) mixture of fluoroethylene carbonate and diethyl carbonate. The battery was typically constructed in a glove box (<1 ppm H₂O and O₂). The water content of the dry matter of all starting materials was preferably less than 20 ppm.

[0136] First, the half-cell is converted to a discharge state by constant current discharge (cc method) until a voltage limit of 0.005V is reached. This constant current corresponds to the C / 25 rate based on the theoretical capacity of the silicon-containing material (theoretical capacity: silicon weight % * 3579 mAh / g; rate: C / 25 corresponds to the charge / discharge over a 25-hour period). Here, the active material is lithium-based.

[0137] The reversible delithiation capacity β of the anode coating was determined by subsequently charging the produced button half-cells, which were discharged in this manner at C / 25, until the voltage limit of 1.5V was reached.

[0138] Electrochemical measurements were performed at 20°C.

[0139] Measurement of average particle resistance:

[0140] To measure the resistance of individual particles smaller than 100 μm, a flat copper indenter was fitted to the Shimadzu Microcompression Tester MCT211, which was connected to a KEITHLEY 2602 dual-source instrument along with the sample holder. Due to the varying geometries of different particles, the resistance values ​​of individual particles are dispersed. Therefore, the average resistance of at least 20 individual particles was measured for each product batch. Statistical analysis using a t-test [One-sample test, Student: The Probable Error of a Mean. In: Biometrika. Volume 6, No. 1 March 1908, pp. 1-259] then determined significant differences between the means of different product batches at, for example, a 95% confidence level.

[0141] Example 1:

[0142] Porous particles of silica:

[0143] Initially, 493 ml of ethanol and 308 ml of water were placed in a 1 L wide-necked Duran glass bottle. 30.18 g of tetraethoxysilane (TEOS) was added to the mixture at room temperature and dissolved with stirring. The solution temperature was maintained at 15 °C, and another 30.18 g of TEOS was added over a 45-minute period using a dropping funnel. The solution slowly became cloudy, forming a precipitate. The reaction mixture was stirred at 15 °C for another 4 hours. The precipitate was then filtered by suction and washed four times with water and ethanol. The resulting white powder was dried in an oven at 80 °C for 4 hours. The crude product (18.68 g) was heated to 400 °C in a boat in a tube furnace at a heating rate of 2 °C / min. The temperature was maintained at approximately 10 °C / min until the next 600 °C was reached, and held for 4 hours. The furnace atmosphere was adjusted by an argon flow rate of 12 L / h throughout the reaction and 3 L / h during the cooling phase until the tube was emptied. 13.74 g (73.6%) of porous SiO2 particles were obtained.

[0144] Reversible delithiation capacity β: 8mAh / g

[0145] BET: 1270m 2 / g

[0146] Particle size distribution (PSD): D 50 =5.4μm, span 0.77

[0147] Total pore volume: 0.8 cm³ 3 / g

[0148] Average particle resistance: 240,000 kOhm

[0149] Example 2:

[0150] Silicon-containing materials:

[0151] 3.0 g of porous silica particles (specific surface area = 1070 m²) from Example 1 were loaded into a tubular reactor in a quartz glass boat. 2 / g, pore volume = 0.6cm³ 3 / g). After inerting with nitrogen, the reactor was heated to 410°C. Once the reaction temperature was reached, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5.8 hours. The reactor was then purged with inert gas, and the product was annealed at 500°C for 1 hour. Before being removed from the reactor, the product was cooled to room temperature under inert gas.

[0152] BET surface area: 29m² 2 / g

[0153] PSD:D 50 =5.4μm, span 0.77

[0154] Deposited Si content: 35% by weight

[0155] Reversible delithiation capacity β: 1245mAh / g

[0156] Initial coulomb efficiency: 92%

[0157] Comparative Example 3:

[0158] Silicon-containing materials:

[0159] 3.0 g of mesoporous silica matrix (specific surface area = 360 m²) was added to the tubular reactor. 2 / g, pore volume = 1.1cm³ 3 / g, from Macherey-Nagel's Polygoprep TM (100-12, average particle resistivity 210,000 kΩ, reversible capacity β = 8 mAh / g). After inerting with nitrogen, the reactor was heated to 410 °C. After reaching the reaction temperature, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5 hours. The reactor was then purged with inert gas, and the product was annealed at 500 °C for 1 hour. Before being removed from the reactor, the product was cooled to room temperature under inert gas.

[0160] BET: 214m 2 / g

[0161] PSD:D 50 =14μm, span 0.8

[0162] Deposited Si content: 30% by weight

[0163] Reversible delithiation capacity β: 1068mAh / g

[0164] Initial coulomb efficiency: 89%

[0165] Example 4:

[0166] Electrochemical testing in anodes containing silicon-containing materials from Example 2 and in lithium-ion batteries:

[0167] 29.71 g of polyacrylic acid (dried to constant weight at 85°C; Sigma-Aldrich, Mw ~ 450,000 g / mol) and 756.60 g of deionized water were stirred for 2.5 hours using a shaker (290 l / min) until the polyacrylic acid was completely dissolved. Lithium hydroxide monohydrate (Sigma-Aldrich) was added aliquoted to the solution until the pH reached 7.0 (measured using a WTW pH 340i pH meter and a SenTix RJD probe). The solution was then further mixed using a shaker for 4 hours. Initially, 3.87 g of the neutralized polyacrylic acid solution and 0.96 g of graphite (Imerys, KS6L C) were placed in a 50 ml container and mixed at 2000 rpm in a planetary mixer (SpeedMixer, DAC 150SP). Subsequently, 3.40 g of the silicon-containing material according to the invention from Example 2 was stirred at 2000 rpm for 1 minute. Then add 1.21 g of 8% conductive carbon black dispersion and 0.8 g of deionized water, and combine in a planetary mixer at 2000 rpm. Then disperse in a dissolver at 3000 rpm at a constant 20°C for 30 minutes. Degas the ink again in a planetary mixer under vacuum at 2500 rpm for 5 minutes.

[0168] The completed dispersion was then applied to a 0.03 mm thick copper foil (Schlenk metal foil, SE-Cu58) using a film stretching frame (Erichsen, model 360) with a gap height of 0.1 mm. The resulting anodic coating was then dried at 50 °C and 1 bar air pressure for 60 minutes. The average basis weight of the dried anodic coating was 3.0 mg / cm³. 2 And the coating density is 0.7 g / cm³. 3 .

[0169] Electrochemical studies were conducted on a coin cell (CR2032 type, Hohsen Corp.) with a two-electrode arrangement. The electrode coating was used as either the counter or anode (Dm = 15 mm); a content of 94.0% and an average basis weight of 15.9 mg / cm³ were used. 2 A 6:2:2 coating of lithium nickel manganese cobalt oxide (obtained from SEI) was used as the working electrode or positive electrode (Dm = 15 mm). Glass fiber filter paper (Whatman, GD Type D) saturated with 60 μl of electrolyte was used as the separator (Dm = 16 mm). The electrolyte consisted of a 1.0 mol solution of lithium hexafluorophosphate in a 1:4 (v / v) mixture of ethylene fluorocarbonate and diethyl carbonate. The battery was constructed in a glove box (<1 ppm H₂O, O₂); the water content in the dry matter of all components used was less than 20 ppm.

[0170] Electrochemical tests were conducted at 20°C. Using the cc / cv method (constant current / constant voltage), the battery was charged at a constant current of 5 mA / g (corresponding to C / 25) in the first cycle, and at a constant current of 60 mA / g (corresponding to C / 2) in subsequent cycles. Upon reaching the voltage limit of 4.2V, the battery was charged at a constant voltage until the current dropped below 1.2 mA / g (corresponding to C / 100) or 15 mA / g (corresponding to C / 8). Using the cc method (constant current), the battery was discharged at a constant current of 5 mA / g (corresponding to C / 25) in the first cycle, and at a constant current of 60 mA / g (corresponding to C / 2) in subsequent cycles until reaching the voltage limit of 2.5V. The specific current selected was based on the weight of the positive electrode coating. The electrode was selected with a cathode:anode capacitance ratio of 1:1.2.

[0171] The following test results were obtained using the all-lithium-ion battery cell of Example 4:

[0172] - Reversible specific capacity of the negative electrode in the second cycle:

[0173] 600mAh / g(4.2–2.5V); 534mAh / g(4.2–3.0V)

[0174] - Number of cycles with ≥80% capacity retention:

[0175] 302 charge / discharge cycles.

[0176] Comparative Example 5:

[0177] Electrochemical tests in lithium-ion batteries using silicon-containing materials from Comparative Example 3:

[0178] An anode was prepared using a non-inventive silicon-containing material from Comparative Example 3, as described in Example 4. The anode was then installed in a lithium-ion battery as described in Example 4 and tested using the same procedure.

[0179] The following test results were obtained using the all-lithium-ion battery cells of Comparative Example 5:

[0180] - Reversible specific capacity of the negative electrode in the second cycle:

[0181] 520mAh / g(4.2–2.5V); 490mAh / g(4.2–3.0V)

[0182] - Number of cycles with ≥80% capacity retention:

[0183] 35 charge / discharge cycles.

[0184] Example 6:

[0185] Microporous boron nitride as porous particles:

[0186] 3.36 g of boric acid and 13.68 g of dicyandiamide were dissolved in 300 ml of distilled water at room temperature. The solution was then heated to 100 °C and evaporated with stirring until a white crystalline solid (16.79 g) was obtained. 8.15 g of the resulting intermediate was then placed in a quartz glass boat and placed in a tube furnace. It was heated to 975 °C at a rate of 10 K / min under a syngas stream (5% H2 in N2, 12 Nl / h). After reaching the target temperature, the gas stream was switched to CO2 (3 Nl / h) and held for 5 hours. Finally, the mixture was passively cooled to room temperature under a syngas stream (3 Nl / h). This yielded 0.5 g of a white solid.

[0187] BET surface area: 1006m² 2 / g

[0188] Total pore volume: 0.56 cm³ 3 / g

[0189] Reversible delithiation capacity β: 5mAh / g

[0190] Average particle resistance: 72,740 kΩ

[0191] PSD:D 50 =6.8μm, span 0.81

[0192] Example 7:

[0193] Silicon-containing material having porous particles as described in Example 6:

[0194] 3.0 g of porous BN particles from Example 6 were loaded into a tubular reactor in a quartz glass boat. After inerting with nitrogen, the reactor was heated to 410 °C. Once the reaction temperature was reached, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5.2 hours. The reactor was then purged with an inert gas, and the product was annealed at 500 °C for 1 hour. Before being removed from the reactor, the product was cooled to room temperature under an inert gas atmosphere.

[0195] BET surface area: 14m² 2 / g

[0196] PSD:D 50 =6.8μm, span 0.81

[0197] Deposited Si content: 35% by weight

[0198] Reversible delithiation capacity β: 1210mAh / g

[0199] Example 8:

[0200] Electrochemical testing in a lithium-ion battery with an anode containing silicon material from Example 7:

[0201] The anode was prepared using the silicon-containing material of the present invention described in Example 7, as described in Example 4. The anode was then installed in a lithium-ion battery as described in Example 4 and tested using the same procedure.

[0202] The following test results were obtained using the all-lithium-ion battery cell of Example 8:

[0203] - Reversible specific capacity of the negative electrode in the second cycle:

[0204] 740mAh / g(4.2–2.5V); 657mAh / g(4.2–3.0V)

[0205] - Number of cycles with ≥80% capacity retention:

[0206] 280 charge / discharge cycles.

[0207] Comparative Example 9:

[0208] Silicon-containing materials based on porous carbon as porous particles:

[0209] 3.0 g of porous carbon (specific surface area = 1189 m²) was loaded into a tubular reactor in a quartz glass boat. 2 / g, pore volume = 0.65cm³ 3 / g, average particle resistance 1.2 kOhm, reversible capacitance β = 389 mAh / g). After inerting with nitrogen, the reactor was heated to 410 °C. After reaching the reaction temperature, the reaction gas (10% SiH4 in N2, 10 Nl / h) was passed through the reactor for 5.2 hours. The reactor was then purged with inert gas, and the product was annealed at 500 °C for 1 hour. Before being removed from the reactor, the product was cooled to room temperature under inert gas.

[0210] BET surface area: 32m² 2 / g

[0211] PSD:D 50 =3.9μm, span 0.86

[0212] Deposited Si content: 38% by weight

[0213] Reversible delithiation capacity β: 1130mAh / g

[0214] Comparative Example 10:

[0215] Electrochemical tests were conducted on an anode made from silicon-containing material from Comparative Example 9 and in a lithium-ion battery:

[0216] An anode was prepared using a non-inventive silicon-containing material, as described in Example 4, in Comparative Example 9. The anode was then installed in a lithium-ion battery as described in Example 4 and tested using the same procedure.

[0217] The following test results were obtained using the all-lithium-ion battery cells of Comparative Example 10:

[0218] - Reversible specific capacity of the negative electrode in the second cycle:

[0219] 580mAh / g(4.2–2.5V); 464mAh / g(4.2–3.0V)

[0220] - Cycle count with ≥80% capacity retention: 174 charge / discharge cycles.

[0221] Table 1: Electrochemical properties of full cells containing Si active materials (measured):

[0222]

Claims

1. A silicon-containing material for use as an active material in the anode of a lithium-ion battery, based on one or more porous particles and silicon, wherein the silicon is disposed in the pores and on the surface of the porous particles, and the silicon-containing material has a density of up to 50 μm. 2 The specific surface area of ​​ / g, as determined by nitrogen adsorption and BET evaluation, is characterized by, The porous particles have a) Average particle resistance of at least 2 kOhm, and b) Reversible delithiation capacity β of up to 100 mAh / g, The porous particles mentioned above are based on the total composition Al a B b C c Mg d N e O f Si g Ceramic materials, wherein 0 ≤ a, b, c, d, e, f, g ≤ 1; wherein at least two coefficients from a to g are greater than 0 and a*3 + b*3 + c*4 + d*2 + g*4 ≥ e*3 + f*2, comprising ceramic materials selected from the following: - Non-stoichiometric boron nitride (BN) z Where z = 0.2 to 1, - Non-stoichiometric carbon nitride CN z Where z = 0.1 to 4 / 3, -Boron carbonitride B x CN z Where x = 0.1 to 20 and z = 0.1 to 20, and x*3 + 4 ≥ z*3, -Boron nitride oxide (BN) z O r Where z = 0.1 to 1 and r = 0.1 to 1, and 3 ≥ r*2 + z*3. -Boron carbonitride oxide B x CN z O r Where x = 0.1 to 2, z = 0.1 to 1 and r = 0.1 to 1, and x*3+4≥r*2+z*3, - silicon carbide Si x CO z Where x = 0.1 to 2 and z = 0.1 to 2, and x*4 + 4 ≥ z*2, - Silicon carbonitride (Si) x CN z Where x = 0.1 to 3 and z = 0.1 to 4, and x*4+4≥z*3, - boron carbonitride silicon Si w B x CN z Where w = 0.1 to 3, x = 0.1 to 2, and z = 0.1 to 4, and w*4 + x*3 + 4 ≥ z*3, - Si-boron-carbon oxide w B x CO z Where w = 0.10 to 3, x = 0.1 to 2 and z = 0.1 to 4, and w*4 + x*3 + 4 ≥ z*2. - boron carbonitride silicon oxide Si v B w CN x O z Where v = 0.1 to 3, w = 0.1 to 2, x = 0.1 to 4 and z = 0.1 to 3, where v*4 + w*3 + 4 ≥ x*3 + z*2, and -Silicon boron aluminum oxide carbonitride (Al) u B v Si x CN w O z , where u = 0.1 to 2, v = 0.1 to 2, w = 0.1 to 4, x = 0.1 to 2 and z = 0.1 to 3, where u*3+v*3+x*4+4≥w*3+z*2.

2. The silicon-containing material according to claim 1, characterized in that, The porous particles have a density of 0.1 to 7 g / cm³. 3 The density was determined by the helium specific gravity bottle method.

3. The silicon-containing material according to claim 1 or 2, characterized in that, The porous particles have a diameter percentile d 50 The volume-weighted particle size distribution ranges from 0.5 to 20 μm.

4. The silicon-containing material according to claim 1 or 2, characterized in that, The silicon-containing material has a diameter percentile d 50 The volume-weighted particle size distribution ranges from 0.5 to 20 μm.

5. The silicon-containing material according to claim 1 or 2, characterized in that, Based on the total pore volume, the silicon-containing material has up to 30% macropores.

6. The silicon-containing material according to claim 1 or 2, characterized in that, The silicon-containing material has at least 50% pores with a diameter of up to 5 nm.

7. The silicon-containing material according to claim 1 or 2, characterized in that, The silicon-containing material contains at least 30% by weight of silicon.

8. The silicon-containing material according to claim 1 or 2, characterized in that, The silicon exists in the form of a layer of silicon particles with a thickness of up to 1 μm, both inside the pores and on the outer surface of the porous particles.

9. A method for producing a silicon-containing material according to any one of the preceding claims, the method comprising thermally decomposing one or more silicon precursors in the presence of one or more porous particles, thereby depositing silicon in the pores and on the surface of the porous particles, said silicon-containing material having a surface area of ​​up to 50 μm. 2 The specific surface area of ​​ / g, as determined by nitrogen adsorption and BET evaluation, is characterized by, The porous particles have a) Average particle resistance of at least 2 kOhm, and b) Reversible delithiation capacity β of up to 100 mAh / g, The porous particles mentioned above are based on the total composition Al a B b C c Mg d N e O f Si g Ceramic materials, wherein 0 ≤ a, b, c, d, e, f, g ≤ 1; wherein at least two coefficients from a to g are greater than 0 and a*3 + b*3 + c*4 + d*2 + g*4 ≥ e*3 + f*2, comprising ceramic materials selected from the following: - Non-stoichiometric boron nitride (BN) z Where z = 0.2 to 1, - Non-stoichiometric carbon nitride CN z Where z = 0.1 to 4 / 3, -Boron carbonitride B x CN z Where x = 0.1 to 20 and z = 0.1 to 20, and x*3 + 4 ≥ z*3, -Boron nitride oxide (BN) z O r Where z = 0.1 to 1 and r = 0.1 to 1, and 3 ≥ r*2 + z*3. -Boron carbonitride oxide B x CN z O r Where x = 0.1 to 2, z = 0.1 to 1 and r = 0.1 to 1, and x*3+4≥r*2+z*3, - silicon carbide Si x CO z Where x = 0.1 to 2 and z = 0.1 to 2, and x*4 + 4 ≥ z*2, - Silicon carbonitride (Si) x CN z Where x = 0.1 to 3 and z = 0.1 to 4, and x*4+4≥z*3, - boron carbonitride silicon Si w B x CN z Where w = 0.1 to 3, x = 0.1 to 2, and z = 0.1 to 4, and w*4 + x*3 + 4 ≥ z*3, - Si-boron-carbon oxide w B x CO z Where w = 0.10 to 3, x = 0.1 to 2 and z = 0.1 to 4, and w*4 + x*3 + 4 ≥ z*2. - boron carbonitride silicon oxide Si v B w CN x O z Where v = 0.1 to 3, w = 0.1 to 2, x = 0.1 to 4 and z = 0.1 to 3, where v*4 + w*3 + 4 ≥ x*3 + z*2, and -Silicon boron aluminum oxide carbonitride (Al) u B v Si x CN w O z , where u = 0.1 to 2, v = 0.1 to 2, w = 0.1 to 4, x = 0.1 to 2 and z = 0.1 to 3, where u*3+v*3+x*4+4≥w*3+z*2.

10. The method according to claim 9, characterized in that, Silicon is deposited from silicon precursors in a reactor selected from fluidized bed reactors, rotary kilns with horizontal to vertical orientation, open or closed fixed bed reactors, and pressure reactors.

11. An anode material for a lithium-ion battery, comprising 5 to 95% by weight of a silicon-containing material as described in any one of claims 1 or 2, 0 to 90% by weight of one or more other conductive components, 0 to 90% by weight of graphite, 0 to 25% by weight of a binder, and 0 to 80% by weight of other additives, wherein the weight percentages are based on the total weight of the anode material, and the sum of the proportions of all components of the anode material reaches 100% by weight.

12. An anode, comprising a current collector coated with the anode material of claim 11.

13. A lithium-ion battery comprising a cathode, an anode, two conductive connectors to the electrodes, a separator, and an electrolyte impregnating the separator and the two electrodes, and a housing accommodating the above components, characterized in that, The anode comprises the silicon-containing material according to any one of claims 1 or 2.

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